Photocopying – Projection printing and copying cameras – Detailed holder for photosensitive paper
Reexamination Certificate
2003-02-25
2004-11-30
Mathews, Alan (Department: 2851)
Photocopying
Projection printing and copying cameras
Detailed holder for photosensitive paper
C355S053000, C356S400000, C356S401000, C269S071000, C310S311000
Reexamination Certificate
active
06825915
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an alignment device which can position an object to be positioned at a high accuracy within a target accuracy, and specifically to a device suitable for alignment in an apparatus such as a mounting apparatus or an exposure apparatus for wafers, etc.
BACKGROUND ART OF THE INVENTION
For example, in a mounting apparatus for bonding wafers to each other, an aligner for positioning a wafer at a predetermined position in order to processing the wafer or mounting a chip or other parts on the wafer, or an exposure apparatus for performing a predetermined exposure on a wafer, it is necessary to position the wafer at a predetermined position with a high accuracy. As a conventional alignment device used for such positioning of an object to be positioned, for example, used is a device wherein tables adjustable in position in X-axis and Y-axis directions (a horizontal direction) and &thgr; direction (a rotational direction) are stacked and as needed a table or a head adjustable in position in Z-axis direction (a vertical direction) is combined, and in such a device, the positioning accuracy is increased by adjusting and controlling the respective positions in the respective axes directions and the rotational direction.
In such a conventional alignment device, however, because the adjustment is carried out in order with respect to the respective directions (for example, X-axis and Y-axis directions and &thgr; direction), even if a relatively high-accuracy positioning becomes possible only in one direction, there is a case where the positioning accuracy in the direction already adjusted goes wrong when the positioning in the other directions is performed, and consequently, the final positioning accuracy is limited. Further, since usually a mechanical guide is used for positioning, there is a limit in the accuracy of the guide, and also from this point of view, the final positioning accuracy is limited. More concretely, in a conventional alignment device, the possible positioning accuracy is an accuracy which cannot expect a submicron-level positioning, and therefore, a several-ten nanometer-level or several nanometer-level positioning is impossible by the conventional possible positioning accuracy.
Further, as aforementioned, since a conventional alignment device is constructed by stacking tables adjustable in position in X-axis and Y-axis directions and &thgr; direction, when an axis A except an uppermost axis is adjusted, an axis stacked above the axis A must be driven, and therefore, the efficiency of the drive and control for positioning is not good. Moreover, when the device is constructed by stacking tables adjustable in position in X-axis and Y-axis directions and &thgr; direction, the thickness (the size in the vertical direction) of the entire alignment device increases, and therefore, an apparatus incorporating this alignment device, for example, a mounting apparatus or an exposure apparatus, inevitably becomes large-sized. Further, because the distance from a guide to an uppermost positioning surface becomes large, an error of the guide is amplified, and this may give a bad influence to the positioning accuracy.
Furthermore, since the positioning in &thgr; direction is performed by adjusting a position adjusting table around a predetermined center axis, when the size of an object to be positioned, for example, a wafer, is large, particularly the alignment accuracy in the &thgr; direction deteriorates at a radially outer position in proportion to the radius of the wafer.
DISCLOSURE OF THE INVENTION
Accordingly, a purpose of the present invention is to provide an alignment device which is constructed not by stacking position adjusting tables for the respective directions and the rotational direction as in a conventional device, but by enabling to adjust a single movable table holding an object to be positioned in a single plane simultaneously in at least X-axis and Y-axis directions and &thgr; direction, thereby enabling to position the object to a target position at a time only by a specified one-kind position adjusting means, which can perform a high-accuracy positioning in each direction and up to a radially outer portion of the object, the efficiency of the positioning operation of which is good, and which can construct the entire apparatus to be compact.
To achieve the above-described purpose, an alignment device according to the present invention comprises a movable table for holding an object to be positioned, a plurality of movable support means for movably supporting the movable table at a plurality of positions, respectively, means for reading a recognition mark provided on the object or the movable table, and a control means for controlling the drive of the movable support means based on information from the recognition means, and positioning the object within a target accuracy by the control of the control means, wherein each movable support means comprises means having a pair of support blocks each provided to be able to contact/separate with/from the movable table and a pair of piezoelectric actuators each provided with expansible first and second piezoelectric elements extending in a substantially horizontal direction across each other and an expansible third piezoelectric element extending in a substantially vertical direction, the first, second and third piezoelectric elements being connected to a support block, and being capable of walking operation relative to the movable table by the operations that the pair of piezoelectric actuators contact/separate the pair of support blocks with/from the movable table alternately.
Namely, in the above-described alignment device, in each piezoelectric actuator of each movable support means, the support block is brought into contact with or separated from the movable table by the expansion and contraction operation (hereinafter, merely referred to as expansion operation in this specification) of the third piezoelectric element, and the support block is moved in the two-dimensional direction, that is the horizontal direction, by the expansion operations of the first and second piezoelectric elements, and accompanying with the movement, the third piezoelectric element is swung. The third piezoelectric element is repeatedly brought into contact with and separated from the movable table via the support block, accompanying therewith the swing operation is repeated, and by the condition where this operation is performed for each piezoelectric actuator of the pair of piezoelectric actuators alternately, two third piezoelectric elements operate as if they were in a walking motion relative to the movable table, and this motion is exhibited as the walking operation. This walking operation is a relative operation to the movable table, and actually, the movable table side is moved by driving the plurality of movable support means. By controlling the drive of the plurality of movable support means, the movable table can be adjusted in position in a single plane simultaneously in X-axis and Y-axis directions (horizontal direction) and &thgr; direction (rotational direction), and besides, the position of the rotational center can also be controlled arbitrarily, and therefore, the object can be moved to a target position with a high accuracy at a time by the specified movable support means using piezoelectric elements.
In this positioning, because basically it is not necessary to have a mechanical guide structure, the positioning accuracy is not limited originating from the mechanical guide structure. Further, because the movable table can be driven in a single plane simultaneously in X-axis, Y-axis and &thgr; directions by the drive of the plurality of movable support means, the distance up to the positioning surface on the movable table or on the object held on the movable table may be small from the viewpoint of this drive system due to the plurality of movable support means, and therefore, there does not occur a problem of amplification of an control error in the drive of t
Arai Yoshiyuki
Inaka Chisa
Moriwaki Toshimichi
Shamoto Eiji
Yamauchi Akira
Mathews Alan
Smith Patent Office
Toray Engeneering Co., Ltd.
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